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The Westbank Irrigation District Powers Creek Water Treatment Plant - PDF

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The Westbank Irrigation District Powers Creek Water Treatment Plant - PDF Powered By Docstoc
					The Westbank Irrigation District Powers Creek Water Treatment Plant
                                               The Westbank Irrigation District (WID) is an
                                               improvement district operating under the authority
                                               of the Local Government Act. It has a letters patent
                                               managed by five elected Trustees. WID is located
                                               in West Kelowna across the Okanagan Lake from
                                               the City of Kelowna. The area is well known for its
                                               sunny hot summers, friendly people, and wineries.
                                               WID serves a population of approximately 14,000
                                               of the 29,000 within the boundary of the District of
                                               West Kelowna. The WID’s water distribution system
                                               has 5,300 service connections. The construction of
                                               the water treatment plant was approved by
                                               ratepayers in 2005 to improve the safety and
   Powers Creek Water Treatment Plant          quality of drinking water, especially during the
                                               spring freshet.
Overview
The original water system was built in the 1920's and consisted of the Powers Creek watershed
and Powers Creek. The uplands water system is comprised of six reservoir lakes (Tadpole;
Dobbin; Horseshoe; Paynter; Jackpine; and Lambly
(Bear) reservoirs). During the summer months
base water flows are established from the upper
elevation lakes and daily flow variations are
managed via an automated head gate control at the
Lambly reservoir. Construction of the Powers
Creek Water Treatment Plant (PCWTP) was
started in October 2005 and completed on
schedule and under budget in February 2007.
The $18,800,000 project included the cost of
constructing the treatment plant, an 8 ML reservoir;
and the addition of UV disinfection in 2008.

Powers Creek Water Treatment Plant                                Powers Creek WTP Intake
The facility offers a multi-barrier process that consists of an existing intake structure which
receives water directly from Powers Creek and channels the water via gravity through a rotating
screen, flash/rapid mix, coagulation, flocculation, clarification, and filtration processes. The
unique part of the Powers Creek water treatment plant is that the clarification and filtration
processes are combined within the same treatment cell. This combined process is referred to
as In-Filter Dissolved Air Flotation (In-Filter DAF). The Powers Creek water treatment plant is
the largest In-Filter DAF plant in Canada.
The treated water is then pumped approximately 10 metres vertically to an 8 ML treated water
reservoir. Prior to entering the reservoir the treated water is further treated with both ultra violet
and chlorine disinfection processes.
                                                 2

Classification:
Level 4 Water Treatment Plant

Plant Specifications:
Nominal Capacity:          54 ML/day
Hydraulic Capacity:        81 ML/day
Average Daily Flow:        13.7 ML/day
Annual Peak Flow:          38 ML/day
Annual Minimum Flow:       5 ML/day
2 Process trains           3 Cells/train

Intake:
Screening at the intake permits the
removal of large objects such as logs,
leaves, fish and other large foreign
objects.

 •   Water from Powers Creek is fed to
     the plant by gravity from the intake.
                                                      Powers Creek WTP & Reservoir
Flash Mixing:
The primary purpose of the flash mix process is to rapidly mix and equally distribute the
coagulant chemical throughout the raw water.
 Specifications:
 •   The coagulant, Polyaluminum Chloride (PAC), is added and mixed rapidly as the raw
     water enters the facility. The mixing process must be complete and uniform to achieve the
     proper results.

Coagulation/Flocculation Tanks:
Coagulation is the process of clumping fine particles into larger particles, this increase is size
and density will allow for removal by settling, skimming and filtering. Flocculation is the process
of gentle mixing; this brings the particles together to increase size.
 Specifications:
 Tanks –                6             (3 per train)
 Volume -               152 m3        (456 m3 per train)
 •   Flocculation tank is a continuation of the mixing process without the velocity.
 •   The mechanical flocculators are vertical propellers
 •   Flocculation basins are baffled to prevent short-circuiting of the water

Clarification – In-Filter Dissolved Air Flotation (In-Filter DAF):
Clarification is achieved by dissolving air in pressurized filtered water and then releasing the
pressure to cause tiny air bubbles to be formed. These very tiny air bubbles attach themselves
to the floc particles where they then float to the surface where the sludge is slowly removed by
mechanical sweepers. The fact that filtration is part of the same process as clarification permits
a smaller building footprint and reduced construction costs while achieving the treatment quality.
                                                           3




 Specifications:
 Tanks-           6               (3 per train)
 Volume -         156 m3          (468 m3 per train)
 •   Clarified water then slowly moves
     downward through filter medium in the
     bottom of the same treatment cell.


              Flocculation and In-Filter DAF
              Clarification process area. The area
              shown is the 3 treatment cells of train 1.


Filtration:

Filtration is the removal of particulate impurities and floc by passing the water through a filter
bed. The impurities can consist of suspended materials (fine silts/sand and clay), colour
colloids, and biological (bacteria) organisms.
 •   First, the water is filtered through a 600 mm layer of anthracite;
 •   Then the water passes through a 300 mm layer of specially graded sand.
 •   The sludge removed at the surface of this treatment cell is transported by gravity to
     concrete storage chambers. A centrifuge processes the sludge to produce a cake which is
     transported by truck to a designated landfill site.
 Specifications:
 Number of Filters                  6 (one filter bed located at the bottom of each clarification cell)
 Filtration Rate                    10.7 m/hr
 Filter Size                        6.0 m X 5.85 m
 Total Filter Depth                 900 mm thickness
 1st Medium – Anthracite            600 mm thickness
                                                4

 2nd Medium – Sand            300 mm thickness
 Backwash Rate                550 L/sec or 33 m3 per minute
 Air Scour Rate               30 m3/min at 5 psi
 •   After filtration the water flows through a specially designed under-drain that prevents the
     filter medium from passing through but allows filtered water passage.
 •   Filter run times vary from 48 to 120 hours depending on water source and quality.
 •   Run time before backwashing a filter is determined by a combination of particle counts,
     turbidity, and head loss, and is done by mechanical means. This consists of blowers for air
     scour and vertical turbine pumps for backwash water

Pumping:
Filtered water passes into a clearwell by gravity to be pumped to disinfection and then to the
main balancing reservoir or to be pumped as backwash water for filter bed regeneration.
There are two large pumps and two small pumps used to pump water from the clearwell. The
filtered water in the clearwell is handled in two different ways:
 •   The large pumps are used for pumping
     filtered water to the disinfection process and
     to the 8 ML treated water reservoir in the
     summer months and for backwashing the
     filter medium of treatment cells.
 •   The smaller pumps are used mainly during
     the winter months to pump filtered water to
     the disinfection process and to the 8 ML
     treated water reservoir.
                                      Filtered Water
                                      Pump Room
 Specifications:
 Clearwell                    634 m3
 Pumps – Large                (2)    125 Hp            417 L/sec at 15 m head
 Pumps – Small                (2)    30 Hp             104 L/sec at 15 m head
Future provision is allowed for 1 additional large pump when the plant is expanded to 82 ML/d.

Disinfection:
Disinfection is the selective destruction of pathogenic organisms. The Powers Creek water
treatment plant utilizes two forms of disinfection as follows:
 •   UV Disinfection:
     A Trojan UV Swift 4L24 ultra violet reactor is first utilized to provide a 3-log (99.9%)
     reduction of Cryptosporidium and Giardia. This one reactor is designed to treat peak
     water flows for both the present design of 54 ML/d as well as for the ultimate expanded
     water treatment plant capacity of 81 ML/d.
 •   Chlorine Disinfection:
     Post chlorination is used after UV disinfection to provide final disinfection and to provide
     for residual disinfection within the distribution system.
     An end-of-line residual chlorine monitoring station was constructed in 2008 and this facility
     communicates to the water treatment plant to ensure that chlorine disinfection is
                                                   5

     maintained at effective levels throughout the
     distribution system. This facility will also help to
     minimize the amount of chlorine required for this
     purpose.
     The In-Filter DAF water treatment process
     significantly reduces the amount of chlorine
     required to effectively disinfect the water delivered
     to customers. Annual chlorine used at the PCWTP
     is approximately 30% of that required prior to
     treatment.

                            Trojan Swift 4L24 UV Reactor



 Specifications:
 UV Disinfection               Trojan Swift 4L24       4 UV lamps (capacity for 8 UV lamps);
                                                       Dual-action sleeve cleaning system;
                                                       High efficiency electronic ballasts;
                                                       UV output adjusted from 30% to 100%;
 Chlorine Disinfection         Gaseous chlorine        1 metric ton cylinders;
                                                       2 chlorine cylinders on line;
                                                       2 chlorine cylinders on stand-by;
                                                       Emergency shut-offs installed.

Balancing Reservoirs:
After disinfection the fully treated water is stored in the balancing reservoir No. 1 adjacent to the
Powers Creek water treatment plant. There are 3 additional balancing reservoirs within the
distribution system.
 Specifications:
 Balancing Reservoir No.1              8 ML            2 – 4ML concrete reservoirs
 Smith Creek Reservoir                 2 ML            3 – 0.67 ML concrete reservoirs
 Glenrosa Reservoir                    1.9 ML          1 – circular concrete reservoir
 Evergreen Reservoir                   0.4 ML          2 – 0.2 reservoirs




                                                                          Powers Creek WTP, UV
                                                                          Disinfection Chamber &
                                                                          8 ML Balancing
                                                                          Reservoir No.1
                                                  6




Lab Data:       (Values are for 2008)

                                    Turbidity Alkalinity Hardness      pH                Color
                                        NTU      mg/l     mg/l      - Log H+ Apparent        True
     Raw Creek Water Average            1.34    33-50    33-56      6.3 – 7.8    20-80       14-60

       Treated Water      Average       0.05     44        52         6.9       1.2 - 0.6        <3


Operation:
The Westbank Irrigation District Powers Creek Water Treatment Plant and distribution system
are operated and maintained by highly trained and certified operators. The plant contains a
modern laboratory where water quality is monitored; which in turn assists the operators to adjust
the plant performance to meet or exceed provincial drinking water quality objectives established
by Interior Health as well as federal Canadian Drinking Water Quality objectives.

Cost of Water Treatment Operations:            (based on total water demand for 2008)
 •   Labour:                  $0.047/m   3

 •   Chemicals:               $0.042/m3
 •   Other:                   $0.037/m3
 •   Total:                   $0.127/m3

 •   PCWTP Long Term Loan:              Costs based on total water demand for 2008
                                        ($11 million @ 4.4948%; 20 year amortization)
            o   Contribution from users:                     $0.1129/m3
            o   Contribution from New Development:           $0.0479/m3
            o   Total Cost of Long Term Loan:                $0.1608/m3

Operations Staff:
 •   Steve McGill               – EOCP Water Distribution – Level 4;
                                – EOCP Water Treatment – Level 1;
                                – AWWA Cross Connection Control Specialist.
 •   Ole Christensen            – EOCP Water Distribution – Level 3;
                                – EOCP Waste Water Treatment - Level 1;
                                – EOCP Chlorine Handling Certificate;
 •   Vince Woytas               – EOCP Water Distribution – Level 1;
                                – EOCP Chlorine Handling Certificate.
 •   Josh Visscher              – EOCP Water Distribution – Level 2.
 •   Mark Maxson                – EOCP Waste Water Treatment - Level 4;
                                – EOCP Water Treatment – Level 1;
                                – EOCP Water Distribution – Level 1;
                                – EOCP Chlorine Handling Certificate.
                                                 7

Distribution System:
 •   80 Kilometres of water mains;
     300+ fire hydrants;
 •   4 distribution pump houses;
     4 reservoirs; total storage of 12.3 ML;
 •   5374+ service connections.

Other Information:
 •   Treatment plant provides protection against Giardia Lamblia, Cryptosporidium, water-
     borne bacteria, and viruses.
 •   Facility is operated by water sourced from 6 upland reservoir lakes within the Powers
     Creek watershed.
 •   Treated water is adjusted for a pH of 6.9 by the addition of caustic soda prior to distribution
     to customers.
 •   A very sophisticated SCADA system controls both the water treatment facility and the
     distribution system from a single location.
 •   A diesel generator provides backup power with the ability to run 50% (train 1) of the water
     treatment plant at full load capacity.
 •   All water testing is accomplished by a third party laboratory. Water quality testing for
     effective water treatment is done at the water treatment site laboratory.

Engineer: Earth Tech (Canada) Inc. (now AECOM) performed the pilot testing of the Powers
    Creek water as well as the preliminary & detailed engineering design & construction
    management for the PCWTP and the 8 ML Balancing Reservoir No. 1.
General Contractor: Maple Reinders Inc. managed the construction of the PCWTP and
    Balancing Reservoir No. 1 over a 17 month period from October 2005 to February 2007.

Residuals Management:
There are two types of waste residual that is produced by the Powers Creek water treatment
plant:
                                                              Residual DAF processing unit.
 •   Liquid Residuals: Produced from the
     backwashing of treatment cell filter medium;
 •   Solid Residuals: Produced from the sludge
     collected from the DAF clarification process.
Liquid Residuals Treatment:
Water used for backwashing filter medium is
stored in the backwash reservoir within the
treatment plant and then processed through a
stand alone Residual DAF clarification unit. The
sludge produced from this process returns to the
sludge storage containment for further
processing by the centrifuge. The clarified water
(centrate) leaving the residual DAF unit is
transported by gravity directly to an engineered
wetland area. The water slowly moves through the wetlands and ultimately decants into Powers
Creek.
                                                  8

Solid Residuals Treatment:
All sludge collected from both the primary and residual DAF clarification processes is stored in
the sludge containment within the treatment plant. On a regular basis the sludge is processed
through a centrifuge to produce a cake consisting of all of the inorganic and organic solids as
well as residual chemicals. This sludge cake is deposited into a container and once full the
container is transported to the designated landfill and used as cover.
The centrate returns to the backwash reservoir.
 Specifications:
 Liquid Residual Treatment:        Backwash reservoir:      1     975 m3
                                   Residual DAF unit        1     Corix (DAF380) 2 ML/d
 Solids Residual Treatment:        DAF Sludge Storage:      2     63 m3 each
                                   Centrifuge:              1     Alfa Laval (ALDECG2-40)




                                                          Alfa Laval Centrifuge used to
                                                          produce sludge cake.




Management & Administration:
 •   Brian W. Jamieson, P.Eng. – General Manager.
 •   Ray McCall, C. Tech. – Technical & Process Manager.
 •   Lynda Wachter – Administrative Manager.
 •   Lis Nielsen – Senior Administration Clerk.
 •   Karen Bisceglia – Junior Administration Clerk (part-time).

Westbank Irrigation District Water System Statistics (2008):
 •   Connections:
                    o   Residential: 5004
                    o   Commercial: 192
                    o   Industrial:    34
                    o   Agricultural: 144
                    o   Total:       5374
 •   Water Meters: All connections are metered and a consumption based water metered rate
     will be implemented in 2010.
 •   Total Volume of Water Treated:          4,909 ML
 •   Maximum Daily Demand:                    37.7 ML